The invention is based on an electromagnet as generally defined hereinafter. An electromagnetically actuated valve has already been proposed in which the armature, in the non-excited state, assumes a position spaced apart from the core, while upon electromagnetic excitation the armature is drawn toward the core. In many applications, however, an embodiment of this kind is often undesirable, because for instance, when it is used as an outwardly opening injection valve the electromagnet system must be continuously excited in order to close the valve